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by RattusRattus
Tue Apr 30, 2019 10:43 pm
Forum: Beginners
Topic: Portable power pack recommendations and esimate on baterry life
Replies: 9
Views: 307

Re: Portable power pack recommendations and esimate on baterry life

given 1.25W for the display then 3.5-4W Load is going to be slightly lower than my projections, so expect slightly better battery life :-)
by RattusRattus
Tue Apr 30, 2019 10:38 pm
Forum: Graphics, sound and multimedia
Topic: I2S DAC (amp) vs USB DAC (amp)
Replies: 1
Views: 229

Re: I2S DAC (amp) vs USB DAC (amp)

there is no better or worse. It all comes down to what you want to do to which is better suited to your needs I also disagree with you completely with your assertion : It can produce better audio than I2S DAC (amp) by having more free space for more components. I2S DAC (amp) cannot be big. This is j...
by RattusRattus
Tue Apr 30, 2019 9:58 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: High-speed I/O between a RP3 and an ARM M7
Replies: 1
Views: 162

Re: High-speed I/O between a RP3 and an ARM M7

Quite frankly the SPI port is about as fast as you are going to get without using USB unles you want to be very creative with the MIPI-CSI (Camera) interface.

/Rattus
by RattusRattus
Tue Apr 30, 2019 8:39 pm
Forum: Beginners
Topic: Portable power pack recommendations and esimate on baterry life
Replies: 9
Views: 307

Re: Portable power pack recommendations and esimate on baterry life

H there, Pi will draw typically a couple of Watts (I have a Pi3 running on a custom hat connected to wired Ethernet drawing 400mA running 24x7 so I am pretty happy with that assertion) The real unknown will be the display - the Raspberry Pi 7" Touch screen data-sheet doesn't give any power details, ...
by RattusRattus
Fri Mar 22, 2019 12:47 pm
Forum: Advanced users
Topic: GPIO c/c++ static library
Replies: 2
Views: 248

Re: GPIO c/c++ static library

Personally I use sysfs and no additional library at all

but common methods for GPIO control are well described here: https://elinux.org/RPi_GPIO_Code_Samples

/Rattus
by RattusRattus
Fri Mar 22, 2019 12:02 pm
Forum: Weather station
Topic: I2C bus seems not to work
Replies: 6
Views: 579

Re: I2C bus seems not to work

Hi there Make sure that you have pull up resistors (to 3V3!!) on both I2C lines.... I2C is needs one (and only one) pull up resistor on the bus so it is common to not include (or jumper out) pull up resistors by default If you are not sure post me a link to the schematics for YOUR weather hat and I'...
by RattusRattus
Fri Mar 22, 2019 11:39 am
Forum: Networking and servers
Topic: Ethernet Adapter RPi Zero Problems
Replies: 1
Views: 307

Re: Ethernet Adapter RPi Zero Problems

Your logs seem to suggest a USB subsystem problem, but other than that... Lets try some basic fault finding 1) is it always the SAME Pis that have this error? You mention that some Pis randomly don't start as expected... is it always the same Pis that fail to start (i.e. does Pi #1 always work but P...
by RattusRattus
Fri Mar 22, 2019 11:15 am
Forum: Automation, sensing and robotics
Topic: Wi-Fi Relay & Raspberry
Replies: 4
Views: 209

Re: Wi-Fi Relay & Raspberry

I am really confused by the following statement:
I want to use relays with wifi module to connect them all without connecting all with cables
That sounds like you want to have relays and no wires :-)

Draw a picture :-)

/Rattus
by RattusRattus
Fri Mar 22, 2019 11:09 am
Forum: Troubleshooting
Topic: using arduino with raspberry pi
Replies: 1
Views: 81

Re: using arduino with raspberry pi

Short answer: Yes Longer answer: Instead of directly reading from a sensor connected to your Pi then pushing to firebase simply read your sensor information from your arduino and post to firebase. what do I mean by this? 1) have your arduino perform sensor readings 2) Have the Pi obtain data from yo...
by RattusRattus
Mon Mar 18, 2019 9:00 pm
Forum: General programming discussion
Topic: Mixing C and assembly?
Replies: 18
Views: 1340

Re: Mixing C and assembly?

Well it also used ARMv8 not ARMv6 instructions so you will gain there as well.....

/Rattus
by RattusRattus
Sun Mar 17, 2019 11:16 pm
Forum: General programming discussion
Topic: Mixing C and assembly?
Replies: 18
Views: 1340

Re: Mixing C and assembly?

links inside the ARM document apear to be dead

you will certainly need the Procedure call standard
http://infocenter.arm.com/help/topic/co ... _aapcs.pdf

/Rattus
by RattusRattus
Sun Mar 17, 2019 11:05 pm
Forum: Python
Topic: spi and max7219 issues with custom board
Replies: 2
Views: 322

Re: spi and max7219 issues with custom board

OK before we start to look at software issues lets look at the physical hardware first you have posted partial schematics... that is ok but you are not showing enough connection detail I can see that you are running the data and clock signals through a bunch of Schmitt inverters to clean up the sign...
by RattusRattus
Sun Mar 17, 2019 10:18 pm
Forum: General discussion
Topic: Let's share lifespan optimizations for microSD cards.
Replies: 3
Views: 419

Re: Let's share lifespan optimizations for microSD cards.

You are dealing with Logical blocks only

The wear levelling happens on the physical FLASH

The file system shouldn't matter (That said I am aware that some controllers do performance optimise for FAT32, by careful cache management)


/Andy
by RattusRattus
Sun Mar 17, 2019 9:48 pm
Forum: General programming discussion
Topic: Mixing C and assembly?
Replies: 18
Views: 1340

Re: Mixing C and assembly?

Hi ab1jx So there are absolute rules for mixing assembly and C. Just traps to catch you out.... The calling convention is very much target specific. At the moment that would be "ARMv6 + Hard Floating point" if you want to work on all Pis. of cause if you just want to go 64 bit for a Pi 3 then you co...
by RattusRattus
Mon Dec 03, 2018 3:27 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI + GPI interface
Replies: 4
Views: 2328

Re: SPI + GPI interface

So linux has a GPIO driver that you can play around with from the command line. see /sys/class/gpio I would use that to initially play with the GPIO lines (not the SPI lines) that you conect to the DAC. simply read and write files (direction, value etc) for the appropriate pin Likewise the SPI drive...
by RattusRattus
Wed Nov 21, 2018 3:26 pm
Forum: Advanced users
Topic: pigpio--scheduling a future interrupt
Replies: 2
Views: 1372

Re: pigpio--scheduling a future interrupt

I may have compleatly missunderstood your question.

I am interpreting it as this:
"Is there a way to get an interrupt to happen at a given time without using GPIO lines?"

*IF* that is what you are asking then take a look at "signal ( SIGALRM, <handler>);" in <signal.h>

/Andy
by RattusRattus
Wed Nov 21, 2018 11:56 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI + GPI interface
Replies: 4
Views: 2328

Re: SPI + GPI interface

Please expand your question. I don't understand what you are asking so I can only offer some general advice for now: * The ADS868x is able to interface with the Pi as you have already suggested using SPI and a handful of GPIO lines. * It is 3V3 logic so you will not need any level shift. * The SPI b...
by RattusRattus
Fri Nov 09, 2018 12:47 pm
Forum: Automation, sensing and robotics
Topic: Read Temperature from Omron K3MA
Replies: 7
Views: 1491

Re: Read Temperature from Omron K3MA

if you turn the unit round you will find a nice clear display. When the K3MA is turned on and connected correctly use Mk-I human eyeball to look at the display.... Seriously though... Your question boils down to this: "I have <device> and I want to connect it to my RPi. " The question that you need ...
by RattusRattus
Fri Nov 09, 2018 12:09 pm
Forum: General discussion
Topic: Raspberry pi 30A relay
Replies: 15
Views: 824

Re: Raspberry pi 30A relay

CAUTION I HAVE NOT SEEN THE SCHEMATICS - I AM OFFERING AN OPINION BASED ON YOUR POST AND LOOKING AT THE EBAY ITEM ONLY This looks like there is a power supply to drive the 'solid state' (?) relays sate between the two. As such it looks like you need to give the system mains (either 110 or 240VAV) on...
by RattusRattus
Mon Oct 08, 2018 1:41 pm
Forum: Graphics, sound and multimedia
Topic: Recording sound (and video at the same time) with the Pi 3B+
Replies: 12
Views: 1710

Re: Recording sound (and video at the same time) with the Pi 3B+

indeed The pi would make (and does make) good electonics of an IP camera Debian doesn't use Pis for this because we want nice big lenses and sensors that we can run 24x7 with motor zooms etc etc. hence using semi pro camera gear we then use SDI to take a RAW feed from the camer into the PC we mix on...
by RattusRattus
Mon Oct 08, 2018 11:42 am
Forum: Beginners
Topic: Clearing gpio event detect flag
Replies: 1
Views: 211

Re: Clearing gpio event detect flag

Hi Alvin, I think I have understood your question correctly. You have 4 GPIO inputs and are using them to decode upto 15 switches. So you have already encoded the switches into binary. you get a state change signal which calls your routine. you read the state of all 4 lines, then clear the flag It i...
by RattusRattus
Mon Oct 08, 2018 11:19 am
Forum: General discussion
Topic: Uploads via other GPIO pins
Replies: 1
Views: 158

Re: Uploads via other GPIO pins

I tend to use AVRDUDE
You can bit bang most ardueno's (without bootloader) over GPIO from your Pi. You will need 4 GPIO lines for SPI programming (to connect to /RST SCLK MOSI and MISO on the AVR). You can alocate any free GPIO lines from the Pi for this task

/Andy
by RattusRattus
Mon Oct 08, 2018 11:08 am
Forum: Graphics, sound and multimedia
Topic: Recording sound (and video at the same time) with the Pi 3B+
Replies: 12
Views: 1710

Re: Recording sound (and video at the same time) with the Pi 3B+

I was going for capturing video thanks to a modified Pi camera (ArduCam). If we need several Pis to do the job, that's ok too. one Pi, one PiCamera will be fine. But you will still have an issue with getting sound onto the system as I can't see any mention of a mic input on the ArduCam (but then I ...
by RattusRattus
Thu Oct 04, 2018 4:39 pm
Forum: Advanced users
Topic: Trying to read camera inputs from two Raspberry Pi 2B's through a network
Replies: 1
Views: 322

Re: Trying to read camera inputs from two Raspberry Pi 2B's through a network

If by network you are meaning TCP/IP over Ethernet then sorry it's not going to happen easily. There will be just too much jitter for your depth perception algorythem to cope. To overcomethis you will need to synchonise the timing for both cameras AND have that timing available as part of your proce...
by RattusRattus
Thu Oct 04, 2018 4:29 pm
Forum: General discussion
Topic: Wire setting for my heat sensor with rpi3 b plus
Replies: 4
Views: 377

Re: Wire setting for my heat sensor with rpi3 b plus

Differant modules will have differant pin-outs. The best you can do is use a multi-meter to 'buzz-out' the pins. The DHT11 data sheet tells you the pin numbering for the sensor itself: Pin Description 1, the VDD power supply 3.5~5.5V DC 2 DATA serial data, a single bus 3, NC, empty pin 4, GND ground...

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